1. Field of the Invention
The present invention relates to an input pen for use in a pressure sensitive handwriting input unit.
2. Description of the Related Art
Heretofore, in the case of performing an input operation onto a hard panel or an input operation of fine letters, an input pen was used which is made of a synthetic resin and has a tip with a small radius of curvature, whereas in the case of performing an input operation onto a soft panel or a pointing input operation use was made of an input pen made of a soft elastic material and having a tip with a large radius of curvature. Accordingly, in the prior art, two different types of input pens had to be provided and used depending on the situations of use, which was extremely troublesome.
It is therefore the object of the present invention to provide an input pen capable of solving the above problems.
According to the present invention, in order to achieve the above object, there is provided an input pen for use in a pressure sensitive handwriting input unit, the input pen comprising a pen cylinder having at its front end a front input member made of a synthetic resin and having at its rear end a rear input member made of a soft elastic material such as a rubber.
By providing both ends of the pen cylinder with the input members having different hardnesses and by inverting the input pen in use if necessary, input operations depending on the usage and situations are ensured with a single input pen.
An input tip for a front input member of the inventive input pen may be formed from a curved surface having a radius of curvature ranging from 0.5 mm to 1 mm inclusive.
An input tip for a rear input member of the input pen of the invention may be formed of a curved surface having a radius of curvature ranging from 1.5 mm to 4 mm inclusive. In this manner, the tip of the rear input member has a larger radius of curvature than the tip of the front input member.
The soft elastic material constituting the rear input member may be a rubber such as fluorinated rubber. Preferably, the rear input member is preferably subjected to a chemical reaction with a surface treatment agent to reduce its friction coefficient, thereby ensuring a smooth writing onto the panel. The rear input member may be comprised of a thermoplastic elastomer.
The rear input member may in the form of a cap adapted to be fitted onto the exterior of the rear end of the pen cylinder. The cap-like rear input member may be provided with an exterior with a protrusion which, when inserted into an input pen accommodating portion of a pressure sensitive handwriting input unit, comes into frictional contact with the input pen accommodating portion. Such an protrusion may be a circumferential protrusion. At a position corresponding to that protrusion, a recess may be formed on the outer peripheral surface of the rear part of the pen cylinder. This arrangement will facilitate elastic deformation of the protrusion toward the recess upon the insertion into the input pen accommodating portion.
A writing end of a writing implement such as a ball-point pen may be provided so as to project from the rear end of the pen cylinder which is covered by the cap-like rear input member. Thus, by removing the rear input member of the input pen, ordinary writing can be carried out.
The pen cylinder may have a first annular recess posterior to the front input member and a second annular recess at the position of the rear input member so that a cylindrical holder and the rear input member are simultaneously insert-molded into the first and second annular recesses, respectively, the cylindrical holder and the rear input member being made of the same soft elastic material.